Marian Seldes, a regal personality in New York theater for more than six decades in plays ranging from whodunits to the work of Tennessee Williams, Samuel Beckett and, especially, Edward Albee, died on Monday at her home in Manhattan. She was 86.

Susan Shreve, her sister-in-law, confirmed her death.

Tall, angular and dark-haired, with a commanding, patrician voice and liquid gestures, Ms. Seldes could dominate any scene — so much so that she was sometimes criticized for overacting. She shrugged at that: She knew very well that she cut a distinctive figure.

“I know I’m funny, because I’m eccentric, I’m odd,” she once told an interviewer. “I’m not what you expect.”

She also had it right when she described herself as a theatrical workaholic; she was seldom offstage. Acting, she once said, “defines my life, gives it shape and form.”

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Her co-starring performance in Ira Levin’s 1978 thriller “Deathtrap,” for example, earned her not only a Tony Award nomination but also an entry in Guinness’s book of world records. In the play’s five-year run, she never missed one of its 1,793 performances, playing the wife of a playwright who, despite writer’s block, can still plot a murder. (In the process she outlasted a parade of co-stars: John Wood, Stacy Keach, John Cullum, Robert Reed and Farley Granger.)

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Marian Seldes: Her Many Roles

Her warm-up for that marathon was more than 900 performances in Peter Shaffer’s “Equus,” which opened on Broadway in 1974.

“The theater is my focus,” she said. “It is exactly what I want to do.”

If theater was her métier, Edward Albee was her forte. After serving as Irene Worth’s understudy in Mr. Albee’s “Tiny Alice” on Broadway in 1965, she won a supporting role the following year in another new Albee play, “A Delicate Balance,” as the hysterical daughter of feuding parents (Hume Cronyn and Jessica Tandy). She won a Tony for the performance.

Almost 30 years later years she received reams of praise for her work in a string of Albee plays presented Off Broadway, starting in 1994 with “Three Tall Women,” followed by “The Play About the Baby” in 2001 and “Counting the Ways” in 2003.

In “The Play About the Baby,” Ms. Seldes found her theatrical soul mate in her co-star, Brian Murray. As an older couple introducing their younger counterparts to life’s colder, darker truths, Ms. Seldes and Mr. Murray were by turns sinister, charmingly sophisticated and funny.

The Seldes-Murray chemistry worked again in “Counting the Ways,” the second half of a double bill that also featured three short works by Samuel Beckett. As a married couple engaged in a funny but stealthily serious fencing match over the depth and breadth of their affection for each other, Ms. Seldes and Mr. Murray performed, the reviews said, with balletic perfection.

“Ms. Seldes’s résumé — she is one of the few actors to have performed multiple roles in the Albee canon — puts her in the elite company of such stars of the stage as Colleen Dewhurst and Jessica Tandy,” Peter Markswrote in The New York Times in 2001.

Marian Hall Seldes — who was quick to point out that her name was pronounced SEL-dess, not SEL-deez — was born in Manhattan on Aug. 23, 1928. Her mother, the former Alice Wadhams Hall, was a socialite and descendant of a prominent New York family; her father was the author and critic Gilbert Seldes, a descendant of Jewish immigrants from Russia whose friends included Zelda and F. Scott Fitzgerald, the Gershwins and Irving Berlin. An uncle was the prominent journalist George Seldes.

A childhood accident weighed heavily on her. Six years old at the time, she was riding in a motorboat on a lake with her brother and other children when, following them into the water, she jumped and was hit in the face by the boat’s propeller. The wound required many stitches, done by an emergency-room doctor using thick black thread, and it left both her face and her psyche scarred.

“It was awful and gory for quite a long time,” her daughter, Katharine Andres, told The New York Times Magazine in 2010. “Her mother was beautiful, and Marian felt not beautiful enough. She felt like a failure.”

After attending the Dalton School in Manhattan, Ms. Seldes studied at the School of American Ballet before deciding that what she really wanted to do was act. She put aside her toe shoes in 1946 and enrolled at the Neighborhood Playhouse, where she studied with Sanford Meisner, whom she grew to idolize. “He did not teach us acting,” she wrote in a tribute after his death in 1997, “he prepared us to act.”

She made her stage debut in 1947 as a serving girl in “Medea,” directed by John Gielgud and starring Judith Anderson. She went on to appear in a 1954 Broadway staging of Jean Giraudoux’s “Ondine,” with Audrey Hepburn and Mel Ferrer. She attracted strong notice in 1964, again on Broadway, in Tennessee Williams’s revised version of “The Milk Train Doesn’t Stop Here Anymore.”

In that production, which briefly starred Tallulah Bankhead as Flora Goforth, a wealthy old eccentric nearing death in her Italian villa, Ms. Seldes created the role of Blackie, Flora’s troubled secretary.

Ms. Seldes’s credits were voluminous. She had the title role in “Isadora Duncan Sleeps With the Russian Navy” in 1977. (“Vibrant and funny,” Clive Barnes wrote in The Times.) She was a domineering but burdened patrician mother in Tina Howe’s well-praised “Painting Churches” in 1983. That same year, she was, as Frank Rich wrote in The Times, “a frightening, hard-driving” Queen Margaret alongside Kevin Kline in a Joseph Papp production of “Richard III” in Central Park.

In the 1990s she appeared in Chekhov’s “Ivanov” at Lincoln Center and in the Broadway revival of Jean Anouilh’s “Ring Round the Moon,” which had only a brief run but brought her another Tony nomination for her portrayal of a crusty grande dame who turns into a doting matchmaker.

Her most recent Broadway appearance was in Terrence McNally’s “Deuce” in 2007, in which she and Angela Lansbury played former doubles partners reuniting in old age to be honored at the United States Open.

Ms. Seldes published an autobiography, “The Bright Lights: A Theater Life,” in 1978, and wrote a novel, “Time Together” (1981), about a mother’s death and its effect on her two estranged daughters.

She also wrote book reviews and articles about her travels, some of which appeared in The Times. From 1969 to 1991 she was on the faculty of the Theater Center at the Juilliard School, where her students included Robin Williams, Patti LuPone, William Hurt and Mr. Kline.

Ms. Seldes’s first marriage, to Julian Claman, a TV producer, ended in divorce. In 1990 she married the writer and director Garson Kanin. He died in 1999.

Though mainly a creature of the stage, Ms. Seldes had a considerable television career as well, beginning in the medium’s early days in drama series like “Studio One” and “Philco Television Playhouse.” She also appeared on “Perry Mason,” “Alfred Hitchcock Presents,” “Law & Order,” “Murphy Brown” and “Murder, She Wrote.” In 1995 she was Eleanor Roosevelt in the HBO movie “Truman.” She also played Mr. Big’s mother in an episode of “Sex and the City.”

She had roles in a number of films as well, including George Stevens’s “The Greatest Story Ever Told” (1965); “Digging to China” (1998), with Kevin Bacon; “Town and Country” (2001), with Warren Beatty, Diane Keaton and Goldie Hawn; and “Mona Lisa Smile” (2003), with Julia Roberts.

But she never left the stage for long. In addition to her Albee outings, she played the bombastic director of an amateur theatrical in the 2000 revival of George Kelly’s comedy “The Torch-Bearers” and a dotty denizen of Times Square in 2001 in Neil Simon’s “45 Seconds From Broadway.”

In 2010, she was given a lifetime achievement award at the Tony Awards ceremony. To Ms. Seldes, it simply confirmed that she had succeeded in doing exactly what she had set out to do.

“All I’ve done is live my life in the theater and loved it,” she said. “If you can get an award for being happy, that’s what I’ve got.”